1. Field of the Invention
The present invention relates to a drive train for work vehicles where power from an engine is transmitted to the wheels through an hydrostatic transmission and a mechanical transmission.
2. Description of the Related Art
A conventional transmission structure of a work vehicle includes one in which an engine is mounted to the vehicle body so that its output shaft extends in a fore-and-aft direction of the vehicle and a hydrostatic transmission is mounted rearwardly of the engine such that its pump shaft and motor shaft are oriented in the fore-and-aft direction of the vehicle body, and a mechanical transmission is mounted in a fore-and-aft orientation rearwardly of the hydrostatic transmission such that each of its transmission shafts are oriented in the fore-and-aft direction. An output shaft of the engine is connected to the pump shaft of the hydrostatic transmission and a motor shaft of the hydrostatic transmission is connected to an input shaft of the mechanical transmission. (See, for example, JP2004-50954.)
Another structure is known in which an engine is mounted to the vehicle body so that its output shaft extends in a fore-and-aft direction of the vehicle and a mechanical transmission is mounted in a fore-and-aft orientation rearwardly of the engine such that each of its transmission shafts are oriented in the fore-and-aft direction, and a hydrostatic transmission is mounted rearwardly of the mechanical transmission such that its pump shaft and motor shaft are oriented in the fore-and-aft direction of the vehicle body. An output shaft of the engine is connected to the pump shaft of the hydrostatic transmission and a motor shaft of the hydrostatic transmission is connected to an input shaft of the mechanical transmission. (See, for example, JP2005-178783.)
The structure described above leads to an increased vehicle length due to the fact that the fore-and-aft extending engine, the hydrostatic transmission, and the fore-and-aft oriented mechanical transmission are arranged in the fore-and-aft direction in series.
With structures described above, each of the output shaft of the engine, the pump shaft and motor shaft of the hydrostatic transmission, and each transmission shafts of the mechanical transmission is provided to the vehicle body so as to extend perpendicular to the axles that extend laterally of the vehicle. This structure requires a use of a bevel gear, which is expensive, as the final gear that transmits power from the output shaft of a transmission to the rear axle.